In view of numerous factors such as higher energy prices and environmental concerns, the production of value-added gaseous products from lower-fuel-value carbonaceous feedstocks, such as biomass, coal and petroleum coke, is receiving renewed attention. The catalytic gasification of such materials to produce methane and other value-added gases is disclosed, for example, in U.S. Pat. No. 3,828,474, U.S. Pat. No. 3,998,607, U.S. Pat. No. 4,057,512, U.S. Pat. No. 4,092,125, U.S. Pat. No. 4,094,650, U.S. Pat. No. 4,204,843, U.S. Pat. No. 4,468,231, U.S. Pat. No. 4,500,323, U.S. Pat. No. 4,541,841, U.S. Pat. No. 4,551,155, U.S. Pat. No. 4,558,027, U.S. Pat. No. 4,606,105, U.S. Pat. No. 4,617,027, U.S. Pat. No. 4,609,456, U.S. Pat. No. 5,017,282, U.S. Pat. No. 5,055,181, U.S. Pat. No. 6,187,465, U.S. Pat. No. 6,790,430, U.S. Pat. No. 6,894,183, U.S. Pat. No. 6,955,695, US2003/0167961A1, US2006/0265953A1, US2007/000177A1, US2007/083072A1, US2007/0277437A1 and GB 1599932.
To improve the gasification of coal, techniques have been suggested for admixing coal with a selected catalyst, or catalysts. Known methods include (a) physically admixing of catalyst with the coal, and (b) incipient wetness impregnation, where a catalyst-containing solution is added to a dry coal, and the volume of the solution is not in excess, but is instead just enough to completely fill the pores of the coal. These methods of coal impregnation suffer the drawback of producing a coal with catalyst loading that is not highly dispersed, and thus a coal with reduced gasification efficiency. The art has placed little emphasis on catalyst-loaded coal with highly dispersed catalyst loading, and processes to prepare same. Accordingly, a need exists in the art for providing new catalyst compositions to increase the yield of combustible gaseous products from catalytic coal gasification. At the same time, there is a need for improved methods of catalyst loading that can also be carried out in a manner that permits efficient recycling of the solutions used to load catalyst onto coal, thereby reducing raw materials costs and minimizing the generation of waste products from the catalyst loading process.